Towards a concept of disorders of “higher vestibular function”

Abstract

Background: Vestibular disorders are commonly characterized by a combination of perceptual, ocular motor, postural, and vegetative manifestations, which cause the symptoms of vertigo, nystagmus, ataxia, and nausea. Multisensory convergence and numerous polysynaptic pathways link the bilaterally organized central vestibular network with limbic, hippocampal, cerebellar, and non-vestibular cortex structures to mediate “higher” cognitive functions.Anatomical classification of vestibular disorders: The traditional classification of vestibular disorders is based on the anatomical site of the lesion. While it distinguishes between the peripheral and the central vestibular systems, certain weaknesses become apparent when applied clinically. There are two reasons for this: first, peripheral and central vestibular disorders cannot always be separated by the clinical syndrome; second, a third category, namely disorders of “higher vestibular function”, is missing. These disorders may be caused by peripheral as well as central vestibular lesions.Functional classification: Here we discuss a new concept of disorders of higher vestibular function which involve cognition and more than one sensory modality. Three conditions are described that exemplify such higher disorders: room tilt illusion, spatial hemineglect, and bilateral vestibulopathy all of which present with deficits of orientation and spatial memory.Conclusions: Further elaboration of such disorders of higher multisensory functions with respect to lesion site and symptomatology is desirable. The room tilt illusion and spatial hemineglect involve vestibular and visual function to the extent that both conditions can be classified as either disorders of higher vestibular or of higher visual functions. A possible way of separating these disorders in a first step is to determine whether the causative lesion site affects the vestibular or the visual system. For the vestibular system this lesion site may be peripheral or central. The criterion of “higher function” is fulfilled if cognition or senses other than the primarily affected one come into play.

A Bayesian Account of Visual–Vestibular Interactions in the Rod-and-Frame Task

“…This may arise at the level of the vestibular inputs, but could also arise from a lesion in parietal-occipital areas such as the rSPL (Sierra-Hidalgo et al, 2012). Indeed, a recent study argued that the room tilt illusion arises owing to a cortical mismatch of the visual and vestibular three-dimensional egocentric representation of verticality (Brandt et al, 2014), which is likely to be located in higher-level areas such as the rSPL.…”

Subjective body vertical: a promising diagnostic tool in idiopathic normal pressure hydrocephalus?

“…Thus, the SVV and SBV deviations in iNPH are not caused by a single underlying mechanism, but seem to share common bases [6]. Therefore, a distortion of the SVV and SBV points to a central misperception of gravity in patients with iNPH, and might be classified as a higher vestibular disorder [26]. One could hypothesize that falls of iNPH patients are due to a bilateral central vestibular dysfunction leading to a deviation in the pitch plane, whereas falls in patients with pusher syndrome or Wallenberg's syndrome are due to a unilateral dysfunction of gravicentric pathways which leads to a central vestibular tone imbalance in the roll plane.…”

Deranged Dimensionality of Vestibular Re-Weighting in Multiple Chemical Sensitivity

“…This kind of phenomenon is thought to be determined by maximum likelihood estimation so that the conscious and non-conscious brain processing appears as a near-optimal Bayesian estimator of object properties [56,60]. Furthermore, recent findings have demonstrated disorders of vestibular function as characterized by complex perceptual, sensorimotor and behavioural deficits that exceed basic perceptions of head acceleration or motor responses, such as VOR or vestibulo-spinal reflexes [61,62].…”

“…In turn, recent advances have postulated that additional "higher" vestibular dysfunctional aspects could really result from an impaired integration of the vestibular network within these areas [62]. This integration comprises both the internal representation of the body scheme and the internal model of the surrounding space as well as multisensory motion perception, attention, spatial memory, and navigation [62,66].…”